请看以下代码:
public class SaveViewStateToOther : Page
{ protected DataGrid DataGrid1;
private void Page_Load(object sender, EventArgs e)
{ if (!IsPostBack)
Bind();
}
private void Bind()
{
DataTable table = new DataTable();
table.Columns.Add("id", typeof (int));
table.Columns.Add("name", typeof (string));
for (int i = 0; i < 1000; i++)
{
DataRow row = table.NewRow();
row["id"] = i;
row["name"] = "student_" + i.ToString();
table.Rows.Add(row);
}
DataGrid1.DataSource = table;
DataGrid1.DataBind();}
protected override void SavePageStateToPersistenceMedium(object viewState)
{
LosFormatter format = new LosFormatter();
StringWriter writer = new StringWriter();
format.Serialize(writer, viewState);
string vsRaw = writer.ToString();
byte[] buffer = Convert.FromBase64String(vsRaw);
string vsText = Encoding.ASCII.GetString(buffer);
object v = Cache[PageKey];
if (v == null)
Cache.Insert(PageKey, vsText);
else
Cache[PageKey] = vsText;
}
public string PageKey
{
get { return Session.SessionID + "_page_SaveViewStateToOther_aspx"; }
}
protected override object LoadPageStateFromPersistenceMedium()
{
object s = Cache[PageKey];
if (s != null)
{
string state = s.ToString();
byte[] buffer = Encoding.ASCII.GetBytes(state);
string vsRaw = Convert.ToBase64String(buffer);
LosFormatter formatter = new LosFormatter();
return formatter.Deserialize(vsRaw);
}
return null;
}上面的代码运行正确并且达到目的,当我将Bind()中的内容换成邦定数据库的数据的时候,当页面刷新时,在函数LoadPageStateFromPersistenceMedium的return formatter.Deserialize(vsRaw);出现错误“键不能为空",请问这是什么原因?
public class SaveViewStateToOther : Page
{ protected DataGrid DataGrid1;
private void Page_Load(object sender, EventArgs e)
{ if (!IsPostBack)
Bind();
}
private void Bind()
{
DataTable table = new DataTable();
table.Columns.Add("id", typeof (int));
table.Columns.Add("name", typeof (string));
for (int i = 0; i < 1000; i++)
{
DataRow row = table.NewRow();
row["id"] = i;
row["name"] = "student_" + i.ToString();
table.Rows.Add(row);
}
DataGrid1.DataSource = table;
DataGrid1.DataBind();}
protected override void SavePageStateToPersistenceMedium(object viewState)
{
LosFormatter format = new LosFormatter();
StringWriter writer = new StringWriter();
format.Serialize(writer, viewState);
string vsRaw = writer.ToString();
byte[] buffer = Convert.FromBase64String(vsRaw);
string vsText = Encoding.ASCII.GetString(buffer);
object v = Cache[PageKey];
if (v == null)
Cache.Insert(PageKey, vsText);
else
Cache[PageKey] = vsText;
}
public string PageKey
{
get { return Session.SessionID + "_page_SaveViewStateToOther_aspx"; }
}
protected override object LoadPageStateFromPersistenceMedium()
{
object s = Cache[PageKey];
if (s != null)
{
string state = s.ToString();
byte[] buffer = Encoding.ASCII.GetBytes(state);
string vsRaw = Convert.ToBase64String(buffer);
LosFormatter formatter = new LosFormatter();
return formatter.Deserialize(vsRaw);
}
return null;
}上面的代码运行正确并且达到目的,当我将Bind()中的内容换成邦定数据库的数据的时候,当页面刷新时,在函数LoadPageStateFromPersistenceMedium的return formatter.Deserialize(vsRaw);出现错误“键不能为空",请问这是什么原因?
请各位高手指点,谢谢
private void DataBind()
{
SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["ConnectString"]);
conn.Open();
SqlCommand cmd=conn.CreateCommand();
SqlDataAdapter sa=new SqlDataAdapter();
sa.SelectCommand=cmd;
cmd.CommandType=CommandType.StoredProcedure;
cmd.CommandText="SP_MgMrBasicTblList";
DataSet ds=new DataSet();
sa.Fill(ds);
DataTable dt=ds.Tables[0];
DataGrid1.DataSource=dt.DefaultView;
DataGrid1.DataBind(); }
这样就会出现上面提示的错误